Runner's Forum: Weight Training for legs (How much? How frequent?)

I've weight trained for years and in 2008 I started running.  When I stopped doing my leg workouts in the gym, I found that I could run faster.  Its been almost 10 months since my last leg workout and I want to start back with it, while trying to maintain optimal running performance.  Any suggesctions on type if leg workout I can do in the gym (specific exercises, volume, intensity, etc..)?